1. Field of Invention
The invention relates to bicycle brake and more particularly to a brake operating device having a magnetic type brake sensitivity adjustment arrangement for bicycles (e.g., electric bicycles).
2. Description of Related Art
A conventional brake operating device for an electric bicycle is shown in FIG. 3. The brake operating device comprises a housing 71, a brake lever 72 mounted on the housing 71, a brake cable 73 having one end fastened at the brake lever 72, an operating wire 74 having one end fastened at the housing 71 and being spaced from the brake cable 73, and a contact switch 75 adjacent one end of the operating wire 74.
In a normal pedaling state of the electric bicycle, the brake lever 72 urges the contact switch 75 against the operating wire 74. As a result, the contact switch 75 is closed and the operating wire 74 is deactivated. To the contrary, in response to squeezing the brake lever 72 the contact switch 75 disengages from the brake lever 72 to become open. As a result, the operating wire 74 is activated to pull the brake cable 73 to force brake pads against both sides of the rim of a rotating wheel, thus slowing and stopping the electric bicycle.
Another conventional brake operating device 8 for an electric bicycle is shown in FIG. 4. The device 8 comprises a housing 82 mounted on a handlebar (not numbered), a pivotal brake lever 81 mounted on the housing 82, a magnetic member 83 in the housing 82, and a conductor 84 adjacent the magnetic member 83. A rider may squeeze the brake lever 81 to move the magnetic member 83 relative to the conductor 84 so as to generate a current on the conductor 84 according to Faraday's law of induction. The current can be converted to mechanical energy to brake the electric bicycle.
However, a distance between the magnetic member 83 and the conductor 84 is fixed when the brake lever 81 is not squeezed. Hence, it is impossible of adjusting a brake response time (i.e., brake sensitivity) of a brake lamp if the brake response time is too long or too quick. Thus, the need for improvement still exists.
There have been numerous suggestions in prior patents for brake operating device for bicycles such as U.S. Pat. No. 5,279,179.